This invention relates generallly to an apparatus for absorbing solar power, and more particularly, to solar ovens, solar cells for testing materials at high temperatures, and other solar power receivers of the cavity type.
This invention was an outgrowth of research directed toward development of a solar cavity receiver such as a test cell, for testing the performance of various materials at temperatures on the order of 3000.degree. F. Operation at such temperatures may be a requirement for components of large-scale systems for utilizing solar thermal energy.
Referring to FIG. 1, initially the solar cavity receiver consisted of two major components: (a) a housing 5 and (b) a photothermal absorber 9, or heat exchanger, positioned within the cavity. As shown, the housing defined a coaxial inlet 13 in which a window 15 was mounted for transmission of a concentrated solar beam into the cavity and onto the absorber. As shown, absorber 9 could be a generally dish-shaped member formed with an internal passage 17 for circulation of a heat-transfer fluid through a heat exchanger 19.
After consideration of the above-described receiver, we concluded that significant power losses would occur because part of the incoming solar power would be radiated back through window 15. That is, part of the incoming rays would be reflected back through the window and part of the infrared radiation generated by the heated absorber 9 would be radiated through the window. These power losses would appreciably limit the maximum temperature attainable in the cavity which, as in this case, could be used as a test cell, or as a thermochemical process vessel, a heat source for a thermodynamic cycle engine, etc.